A transistor provides the amplification needed to energize the relay coil, ensuring microcontrollers and low-voltage circuits can operate lights, motors, and other devices safely. This principle is at the heart of countless applications, from home automation to automotive control. The rectangular devices are test connection blocks, used for testing and isolation of instrument transformer circuits. com IEEE Southern Alberta Section PES/IAS Joint Chapter Technical Seminar - November 2016 Protective Relays - Technical Seminar Nov 2016 - Copyright: IEEE 2 Abstract: Protective relays and devices. Previous experience in designing low voltage and medium voltage switchgear, relay panels and custom control panels as an Electrical Engineer at ESSMetron, Denver CO. Its main purpose is to safeguard electrical equipment like transformers, generators, and transmission lines from damage due to. Relays allow low-power electronic signals to control high-power loads, and when paired with a transistor, they become versatile tools in electronics. For example, unselective protection operation during a medium voltage network fault will cause an outage for an unnecessarily large number of consumers. While this is bad, It's not a.